My question is, how and why is Oedipus Tyrannus a tragedy of self-identity? The search for self-knowledge and origins, the recognition of areas of...

In the
simplest terms,is a man who thinks he knows who he is, but clearly he does not.  Part of that,
of course, was perpetrated on him by deception; even worse, it was his parents who deceived
him.

Oedipus thought he was the natural son of a king, the king of Corinth. 
In fact, of course, he is the son of Laius, king...